Many electronic digital printers apply print characters to paper via multiple exposure elements of an exposure device. In some printers, such as the NexPress 2100 from NexPress Solutions LLC, the exposure elements are light emitting diodes (“LEDs”) and the exposure device is an LED printhead.
The LEDs are typically controlled by a printhead driver integrated circuit (“IC”). Each driver IC may control many LEDs, and a printer may include multiple driver ICs.
FIG. 1 is a block diagram of a prior art printhead driver IC board 10 that is used to control LEDs in a digital printer. Board 10 includes driver ICs 20 and 22 mounted on a substrate 12. Input/output pads 13 are placed along one of the long sides of the rectangular shaped driver ICs 20, 22 and are coupled to the LEDs (not shown). Pads 14 are placed along the other long side or “front” side of driver ICs 20, 22 and are coupled to a data bus. In order to connect pads 14 to the data bus, long parallel gold data traces 16 are required on substrate 12 to reach all driver ICs, and a very high number of wire bonds 15 are required to connect all the driver ICs to data traces 16. Host board connection pads 17 are also formed on substrate 12 to connect driver ICs 20, 22 to a host device that is the source of the data.
From the viewpoint of the host data board driver, the number of loads being driven by each data line on board 10 to the driver ICs is very high, since many driver ICs connect to the data traces in parallel and each data line has different signal path lengths. A transmission line analysis of printing systems that include board 10 shows complicated waveform reflections as a result of the uneven paths and unmatched lengths. This causes data speed limitations as well as excessive electromagnetic interference (“EMI”) emissions.
The large number of wire bonds, as well as the long and unmatched in length signal paths on board 10 limit the speed of operation for high-speed data transmission. The parallel traces and the high number of wire bonds also add significant cost to the manufacturing materials and processes.
As the demand for higher speed operation of exposure devices such as LED printheads continues to rise, the need for higher speed transmission of data to the drivers also rises. Further, as the speed of transmission rises, EMI emissions also rise.
Based on the foregoing, there is a need for an improved printhead driver IC and data transfer method that allows for higher data transmission speed, with reduced EMI emissions.